Publications by authors named "Barbara Robbertse"

21 Publications

  • Page 1 of 1

NCBI Taxonomy: a comprehensive update on curation, resources and tools.

Database (Oxford) 2020 01;2020

National Center of Biotechnology Information, National Library of Medicine, National Institutes of Health, 9600 Rockville Pike, Bethesda, MD 20892, USA.

The National Center for Biotechnology Information (NCBI) Taxonomy includes organism names and classifications for every sequence in the nucleotide and protein sequence databases of the International Nucleotide Sequence Database Collaboration. Since the last review of this resource in 2012, it has undergone several improvements. Most notable is the shift from a single SQL database to a series of linked databases tied to a framework of data called NameBank. This means that relations among data elements can be adjusted in more detail, resulting in expanded annotation of synonyms, the ability to flag names with specific nomenclatural properties, enhanced tracking of publications tied to names and improved annotation of scientific authorities and types. Additionally, practices utilized by NCBI Taxonomy curators specific to major taxonomic groups are described, terms peculiar to NCBI Taxonomy are explained, external resources are acknowledged and updates to tools and other resources are documented. Database URL: https://www.ncbi.nlm.nih.gov/taxonomy.
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http://dx.doi.org/10.1093/database/baaa062DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7408187PMC
January 2020

Unambiguous identification of fungi: where do we stand and how accurate and precise is fungal DNA barcoding?

IMA Fungus 2020 10;11:14. Epub 2020 Jul 10.

International Commission on the Taxonomy of Fungi, Champaign, IL USA.

True fungi () and fungus-like organisms (e.g. , ) constitute the second largest group of organisms based on global richness estimates, with around 3 million predicted species. Compared to plants and animals, fungi have simple body plans with often morphologically and ecologically obscure structures. This poses challenges for accurate and precise identifications. Here we provide a conceptual framework for the identification of fungi, encouraging the approach of integrative (polyphasic) taxonomy for species delimitation, i.e. the combination of genealogy (phylogeny), phenotype (including autecology), and reproductive biology (when feasible). This allows objective evaluation of diagnostic characters, either phenotypic or molecular or both. Verification of identifications is crucial but often neglected. Because of clade-specific evolutionary histories, there is currently no single tool for the identification of fungi, although DNA barcoding using the internal transcribed spacer (ITS) remains a first diagnosis, particularly in metabarcoding studies. Secondary DNA barcodes are increasingly implemented for groups where ITS does not provide sufficient precision. Issues of pairwise sequence similarity-based identifications and OTU clustering are discussed, and multiple sequence alignment-based phylogenetic approaches with subsequent verification are recommended as more accurate alternatives. In metabarcoding approaches, the trade-off between speed and accuracy and precision of molecular identifications must be carefully considered. Intragenomic variation of the ITS and other barcoding markers should be properly documented, as phylotype diversity is not necessarily a proxy of species richness. Important strategies to improve molecular identification of fungi are: (1) broadly document intraspecific and intragenomic variation of barcoding markers; (2) substantially expand sequence repositories, focusing on undersampled clades and missing taxa; (3) improve curation of sequence labels in primary repositories and substantially increase the number of sequences based on verified material; (4) link sequence data to digital information of voucher specimens including imagery. In parallel, technological improvements to genome sequencing offer promising alternatives to DNA barcoding in the future. Despite the prevalence of DNA-based fungal taxonomy, phenotype-based approaches remain an important strategy to catalog the global diversity of fungi and establish initial species hypotheses.
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http://dx.doi.org/10.1186/s43008-020-00033-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7353689PMC
July 2020

Improving taxonomic accuracy for fungi in public sequence databases: applying 'one name one species' in well-defined genera with Trichoderma/Hypocrea as a test case.

Database (Oxford) 2017 01;2017

National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20892, USA.

The ITS (nuclear ribosomal internal transcribed spacer) RefSeq database at the National Center for Biotechnology Information (NCBI) is dedicated to the clear association between name, specimen and sequence data. This database is focused on sequences obtained from type material stored in public collections. While the initial ITS sequence curation effort together with numerous fungal taxonomy experts attempted to cover as many orders as possible, we extended our latest focus to the family and genus ranks. We focused on Trichoderma for several reasons, mainly because the asexual and sexual synonyms were well documented, and a list of proposed names and type material were recently proposed and published. In this case study the recent taxonomic information was applied to do a complete taxonomic audit for the genus Trichoderma in the NCBI Taxonomy database. A name status report is available here: https://www.ncbi.nlm.nih.gov/Taxonomy/TaxIdentifier/tax_identifier.cgi. As a result, the ITS RefSeq Targeted Loci database at NCBI has been augmented with more sequences from type and verified material from Trichoderma species. Additionally, to aid in the cross referencing of data from single loci and genomes we have collected a list of quality records of the RPB2 gene obtained from type material in GenBank that could help validate future submissions. During the process of curation misidentified genomes were discovered, and sequence records from type material were found hidden under previous classifications. Source metadata curation, although more cumbersome, proved to be useful as confirmation of the type material designation. Database URL:http://www.ncbi.nlm.nih.gov/bioproject/PRJNA177353
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http://dx.doi.org/10.1093/database/bax072DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5641268PMC
January 2017

Botryosphaeria dothidea: a latent pathogen of global importance to woody plant health.

Mol Plant Pathol 2017 05 13;18(4):477-488. Epub 2016 Dec 13.

Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag x20, Hatfield 0028, Pretoria, South Africa.

Botryosphaeria dothidea is the type species of Botryosphaeria (Botryosphaeriaceae, Botryosphaeriales). Fungi residing in this order are amongst the most widespread and important canker and dieback pathogens of trees worldwide, with B. dothidea one of the most common species on a large number of hosts. Its taxonomic circumscription has undergone substantial change in the past decade, making it difficult to interpret the large volume of literature linked to the name B. dothidea. This pathogen profile synthesizes the current understanding of B. dothidea pertaining to its distribution, host associations and role as a pathogen in managed and natural woody environments. The prolonged latent infection or endophytic phase is of particular importance, as it implies that the fungus can easily pass undetected by quarantine systems in traded living plants, fruits and other plant parts. Infections typically become obvious only under conditions of host stress, when disease symptoms develop. This study also considers the knowledge emerging from the recently sequenced B. dothidea genome, elucidating previously unknown aspects of the species, including mating and host infection strategies. Despite more than 150 years of research on B. dothidea, there is clearly much to be learned regarding this global tree pathogen. This is increasingly important given the stresses imposed on various woody hosts as a result of climate change.

Taxonomy: Botryosphaeria dothidea (Moug. ex Fr) Ces. & De Not, 1863. Kingdom Fungi, Phylum Ascomycota, Class Dothideomycetes, Order Botryosphaeriales, Family Botryosphaeriaceae, Genus Botryosphaeria, Species dothidea.

Host Range: Confirmed on more than 24 host genera, including woody plants, such as Acacia (= Vachellia), Eucalyptus, Vitis and Pistachio.

Disease Symptoms: Associated with twig, branch and stem cankers, tip and branch dieback, fruit rot, blue stain and plant death.

Useful Websites: The Botryosphaeria site for detailed morphological descriptions (http://www.crem.fct.unl.pt/botryosphaeria_site/); Systematic Mycology and Microbiology Laboratory Fungal Database for all literature and associated hosts (https://nt.ars-grin.gov/fungaldatabases/); TreeBASE link for the combined ITS and TEF-1α tree (http://purl.org/phylo/treebase/phylows/study/TB2:S18906); DOE Joint Genome Institute, JGI Mycocosm for the Botryosphaeria dothidea genome (http://genome.jgi.doe.gov/Botdo1_1/Botdo1_1.home.html).
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http://dx.doi.org/10.1111/mpp.12495DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6638292PMC
May 2017

Reference sequence (RefSeq) database at NCBI: current status, taxonomic expansion, and functional annotation.

Nucleic Acids Res 2016 Jan 8;44(D1):D733-45. Epub 2015 Nov 8.

National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Building 38A, 8600 Rockville Pike, Bethesda, MD 20894, USA

The RefSeq project at the National Center for Biotechnology Information (NCBI) maintains and curates a publicly available database of annotated genomic, transcript, and protein sequence records (http://www.ncbi.nlm.nih.gov/refseq/). The RefSeq project leverages the data submitted to the International Nucleotide Sequence Database Collaboration (INSDC) against a combination of computation, manual curation, and collaboration to produce a standard set of stable, non-redundant reference sequences. The RefSeq project augments these reference sequences with current knowledge including publications, functional features and informative nomenclature. The database currently represents sequences from more than 55,000 organisms (>4800 viruses, >40,000 prokaryotes and >10,000 eukaryotes; RefSeq release 71), ranging from a single record to complete genomes. This paper summarizes the current status of the viral, prokaryotic, and eukaryotic branches of the RefSeq project, reports on improvements to data access and details efforts to further expand the taxonomic representation of the collection. We also highlight diverse functional curation initiatives that support multiple uses of RefSeq data including taxonomic validation, genome annotation, comparative genomics, and clinical testing. We summarize our approach to utilizing available RNA-Seq and other data types in our manual curation process for vertebrate, plant, and other species, and describe a new direction for prokaryotic genomes and protein name management.
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http://dx.doi.org/10.1093/nar/gkv1189DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4702849PMC
January 2016

International Society of Human and Animal Mycology (ISHAM)-ITS reference DNA barcoding database--the quality controlled standard tool for routine identification of human and animal pathogenic fungi.

Med Mycol 2015 May 22;53(4):313-37. Epub 2015 Mar 22.

Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Sydney Medical School-Westmead Hospital, Marie Bashir Institute for Infectious Diseases and Bioscurity, University of Sydney, Westmead Millennium Institute, Sydney, Australia

Human and animal fungal pathogens are a growing threat worldwide leading to emerging infections and creating new risks for established ones. There is a growing need for a rapid and accurate identification of pathogens to enable early diagnosis and targeted antifungal therapy. Morphological and biochemical identification methods are time-consuming and require trained experts. Alternatively, molecular methods, such as DNA barcoding, a powerful and easy tool for rapid monophasic identification, offer a practical approach for species identification and less demanding in terms of taxonomical expertise. However, its wide-spread use is still limited by a lack of quality-controlled reference databases and the evolving recognition and definition of new fungal species/complexes. An international consortium of medical mycology laboratories was formed aiming to establish a quality controlled ITS database under the umbrella of the ISHAM working group on "DNA barcoding of human and animal pathogenic fungi." A new database, containing 2800 ITS sequences representing 421 fungal species, providing the medical community with a freely accessible tool at http://www.isham.org/ and http://its.mycologylab.org/ to rapidly and reliably identify most agents of mycoses, was established. The generated sequences included in the new database were used to evaluate the variation and overall utility of the ITS region for the identification of pathogenic fungi at intra-and interspecies level. The average intraspecies variation ranged from 0 to 2.25%. This highlighted selected pathogenic fungal species, such as the dermatophytes and emerging yeast, for which additional molecular methods/genetic markers are required for their reliable identification from clinical and veterinary specimens.
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http://dx.doi.org/10.1093/mmy/myv008DOI Listing
May 2015

Transposable element-assisted evolution and adaptation to host plant within the Leptosphaeria maculans-Leptosphaeria biglobosa species complex of fungal pathogens.

BMC Genomics 2014 Oct 12;15:891. Epub 2014 Oct 12.

INRA-Bioger, UR1290, Avenue Lucien Brétignières, BP 01, 78850 Thiverval-Grignon, France.

Background: Many plant-pathogenic fungi have a tendency towards genome size expansion, mostly driven by increasing content of transposable elements (TEs). Through comparative and evolutionary genomics, five members of the Leptosphaeria maculans-Leptosphaeria biglobosa species complex (class Dothideomycetes, order Pleosporales), having different host ranges and pathogenic abilities towards cruciferous plants, were studied to infer the role of TEs on genome shaping, speciation, and on the rise of better adapted pathogens.

Results: L. maculans 'brassicae', the most damaging species on oilseed rape, is the only member of the species complex to have a TE-invaded genome (32.5%) compared to the other members genomes (<4%). These TEs had an impact at the structural level by creating large TE-rich regions and are suspected to have been instrumental in chromosomal rearrangements possibly leading to speciation. TEs, associated with species-specific genes involved in disease process, also possibly had an incidence on evolution of pathogenicity by promoting translocations of effector genes to highly dynamic regions and thus tuning the regulation of effector gene expression in planta.

Conclusions: Invasion of L. maculans 'brassicae' genome by TEs followed by bursts of TE activity allowed this species to evolve and to better adapt to its host, making this genome species a peculiarity within its own species complex as well as in the Pleosporales lineage.
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http://dx.doi.org/10.1186/1471-2164-15-891DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4210507PMC
October 2014

The Genera of Fungi: fixing the application of type species of generic names.

IMA Fungus 2014 Jun 19;5(1):141-60. Epub 2014 Jun 19.

CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands;

To ensure a stable platform for fungal taxonomy, it is of paramount importance that the genetic application of generic names be based on their DNA sequence data, and wherever possible, not morphology or ecology alone. To facilitate this process, a new database, accessible at www.GeneraofFungi.org (GoF) was established, which will allow deposition of metadata linked to holo-, lecto-, neo- or epitype specimens, cultures and DNA sequence data of the type species of genera. Although there are presently more than 18 000 fungal genera described, we aim to initially focus on the subset of names that have been placed on the "Without-prejudice List of Protected Generic Names of Fungi" (see IMA Fungus 4(2): 381-443, 2013). To enable the global mycological community to keep track of typification events and avoid duplication, special MycoBank Typification identfiers (MBT) will be issued upon deposit of metadata in MycoBank. MycoBank is linked to GoF, thus deposited metadata of generic type species will be displayed in GoF (and vice versa), but will also be linked to Index Fungorum (IF) and the curated RefSeq Targeted Loci (RTL) database in GenBank at the National Center for Biotechnology Information (NCBI). This initial paper focuses on eight genera of appendaged coelomycetes, the type species of which are neo- or epitypified here: Bartalinia (Bartalinia robillardoides; Amphisphaeriaceae, Xylariales), Chaetospermum (Chaetospermum chaetosporum, incertae sedis, Sebacinales), Coniella (Coniella fragariae, Schizoparmaceae, Diaporthales), Crinitospora (Crinitospora pulchra, Melanconidaceae, Diaporthales), Eleutheromyces (Eleutheromyces subulatus, Helotiales), Kellermania (Kellermania yuccigena, Planistromataceae, Botryosphaeriales), Mastigosporium (Mastigosporium album, Helotiales), and Mycotribulus (Mycotribulus mirabilis, Agaricales). Authors interested in contributing accounts of individual genera to larger multi-authored papers to be published in IMA Fungus, should contact the associate editors listed below for the major groups of fungi on the List of Protected Generic Names for Fungi.
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http://dx.doi.org/10.5598/imafungus.2014.05.01.14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4107892PMC
June 2014

Finding needles in haystacks: linking scientific names, reference specimens and molecular data for Fungi.

Authors:
Conrad L Schoch Barbara Robbertse Vincent Robert Duong Vu Gianluigi Cardinali Laszlo Irinyi Wieland Meyer R Henrik Nilsson Karen Hughes Andrew N Miller Paul M Kirk Kessy Abarenkov M Catherine Aime Hiran A Ariyawansa Martin Bidartondo Teun Boekhout Bart Buyck Qing Cai Jie Chen Ana Crespo Pedro W Crous Ulrike Damm Z Wilhelm De Beer Bryn T M Dentinger Pradeep K Divakar Margarita Dueñas Nicolas Feau Katerina Fliegerova Miguel A García Zai-Wei Ge Gareth W Griffith Johannes Z Groenewald Marizeth Groenewald Martin Grube Marieka Gryzenhout Cécile Gueidan Liangdong Guo Sarah Hambleton Richard Hamelin Karen Hansen Valérie Hofstetter Seung-Beom Hong Jos Houbraken Kevin D Hyde Patrik Inderbitzin Peter R Johnston Samantha C Karunarathna Urmas Kõljalg Gábor M Kovács Ekaphan Kraichak Krisztina Krizsan Cletus P Kurtzman Karl-Henrik Larsson Steven Leavitt Peter M Letcher Kare Liimatainen Jian-Kui Liu D Jean Lodge Janet Jennifer Luangsa-ard H Thorsten Lumbsch Sajeewa S N Maharachchikumbura Dimuthu Manamgoda María P Martín Andrew M Minnis Jean-Marc Moncalvo Giuseppina Mulè Karen K Nakasone Tuula Niskanen Ibai Olariaga Tamás Papp Tamás Petkovits Raquel Pino-Bodas Martha J Powell Huzefa A Raja Dirk Redecker J M Sarmiento-Ramirez Keith A Seifert Bhushan Shrestha Soili Stenroos Benjamin Stielow Sung-Oui Suh Kazuaki Tanaka Leho Tedersoo M Teresa Telleria Dhanushka Udayanga Wendy A Untereiner Javier Diéguez Uribeondo Krishna V Subbarao Csaba Vágvölgyi Cobus Visagie Kerstin Voigt Donald M Walker Bevan S Weir Michael Weiß Nalin N Wijayawardene Michael J Wingfield J P Xu Zhu L Yang Ning Zhang Wen-Ying Zhuang Scott Federhen

Database (Oxford) 2014 30;2014. Epub 2014 Jun 30.

National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA, CBS-KNAW Fungal Biodiversity Centre, P.O. Box 85167, 3508 AD Utrecht, The Netherlands, Department of Pharmaceutical Sciences - Microbiology, Università degli Studi di Perugia, Perugia, Italy, Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Marie Bashir Institute for Infectious Diseases and Biosecurity, Sydney Medical School-Westmead Hospital, The University of Sydney, Westmead Millennium Institute, Westmead, Australia, Department of Biological and Environmental Sciences, University of Gothenburg, Box 461, 405 30 Göteborg, Sweden, Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37920, USA, Illinois Natural History Survey, University of Illinois, 1816 South Oak Street, Champaign, IL 61820, USA, Mycology Section, Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3DS, UK, Natural History Museum, University of Tartu, 46 Vanemuise, 51014 Tartu, Estonia, Purdue University, Department of Botany and Plant Pathology, 915 W. State Street, West Lafayette, IN 47907, USA, Institute of Excellence in Fungal Research, and School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand, Imperial College London, Royal Botanic Gardens, Kew TW9 3DS, England, UK, Muséum National d'Histoire Naturelle, Dépt. Systématique et Evolution CP39, UMR7205, 12 Rue Buffon, F-75005 Paris, France, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, P. R. China, Departamento de Biología Vegetal II, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid 28040, Spain, Senckenberg Museum of Natural History Görlitz, PF 300 154, 02806 Görlitz, Germany, Department of Microbiology and Plant Pathology, Forestry Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0001, South Africa, Real Jardín Botánico, RJB-CSIC,

DNA phylogenetic comparisons have shown that morphology-based species recognition often underestimates fungal diversity. Therefore, the need for accurate DNA sequence data, tied to both correct taxonomic names and clearly annotated specimen data, has never been greater. Furthermore, the growing number of molecular ecology and microbiome projects using high-throughput sequencing require fast and effective methods for en masse species assignments. In this article, we focus on selecting and re-annotating a set of marker reference sequences that represent each currently accepted order of Fungi. The particular focus is on sequences from the internal transcribed spacer region in the nuclear ribosomal cistron, derived from type specimens and/or ex-type cultures. Re-annotated and verified sequences were deposited in a curated public database at the National Center for Biotechnology Information (NCBI), namely the RefSeq Targeted Loci (RTL) database, and will be visible during routine sequence similarity searches with NR_prefixed accession numbers. A set of standards and protocols is proposed to improve the data quality of new sequences, and we suggest how type and other reference sequences can be used to improve identification of Fungi. Database URL: http://www.ncbi.nlm.nih.gov/bioproject/PRJNA177353.
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http://dx.doi.org/10.1093/database/bau061DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4075928PMC
February 2015

MycoBank gearing up for new horizons.

IMA Fungus 2013 Dec 17;4(2):371-9. Epub 2013 Dec 17.

CBS-KNAW Fungal Biodiversity Center, Uppsalalaan 8, 3584CT Utrecht, The Netherlands;

MycoBank, a registration system for fungi established in 2004 to capture all taxonomic novelties, acts as a coordination hub between repositories such as Index Fungorum and Fungal Names. Since January 2013, registration of fungal names is a mandatory requirement for valid publication under the International Code of Nomenclature for algae, fungi and plants (ICN). This review explains the database innovations that have been implemented over the past few years, and discusses new features such as advanced queries, registration of typification events (MBT numbers for lecto, epi- and neotypes), the multi-lingual database interface, the nomenclature discussion forum, annotation system, and web services with links to third parties. MycoBank has also introduced novel identification services, linking DNA sequence data to numerous related databases to enable intelligent search queries. Although MycoBank fills an important void for taxon registration, challenges for the future remain to improve links between taxonomic names and DNA data, and to also introduce a formal system for naming fungi known from DNA sequence data only. To further improve the quality of MycoBank data, remote access will now allow registered mycologists to act as MycoBank curators, using Citrix software.
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http://dx.doi.org/10.5598/imafungus.2013.04.02.16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3905949PMC
December 2013

Comparative genomics of a plant-pathogenic fungus, Pyrenophora tritici-repentis, reveals transduplication and the impact of repeat elements on pathogenicity and population divergence.

G3 (Bethesda) 2013 Jan 1;3(1):41-63. Epub 2013 Jan 1.

Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331-8530, USA.

Pyrenophora tritici-repentis is a necrotrophic fungus causal to the disease tan spot of wheat, whose contribution to crop loss has increased significantly during the last few decades. Pathogenicity by this fungus is attributed to the production of host-selective toxins (HST), which are recognized by their host in a genotype-specific manner. To better understand the mechanisms that have led to the increase in disease incidence related to this pathogen, we sequenced the genomes of three P. tritici-repentis isolates. A pathogenic isolate that produces two known HSTs was used to assemble a reference nuclear genome of approximately 40 Mb composed of 11 chromosomes that encode 12,141 predicted genes. Comparison of the reference genome with those of a pathogenic isolate that produces a third HST, and a nonpathogenic isolate, showed the nonpathogen genome to be more diverged than those of the two pathogens. Examination of gene-coding regions has provided candidate pathogen-specific proteins and revealed gene families that may play a role in a necrotrophic lifestyle. Analysis of transposable elements suggests that their presence in the genome of pathogenic isolates contributes to the creation of novel genes, effector diversification, possible horizontal gene transfer events, identified copy number variation, and the first example of transduplication by DNA transposable elements in fungi. Overall, comparative analysis of these genomes provides evidence that pathogenicity in this species arose through an influx of transposable elements, which created a genetically flexible landscape that can easily respond to environmental changes.
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http://dx.doi.org/10.1534/g3.112.004044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3538342PMC
January 2013

Phylogenomic evidence for a common ancestor of mitochondria and the SAR11 clade.

Sci Rep 2011 14;1:13. Epub 2011 Jun 14.

Departments of Microbiology, Oregon State University, Corvallis, OR 97331, USA.

Mitochondria share a common ancestor with the Alphaproteobacteria, but determining their precise origins is challenging due to inherent difficulties in phylogenetically reconstructing ancient evolutionary events. Nonetheless, phylogenetic accuracy improves with more refined tools and expanded taxon sampling. We investigated mitochondrial origins with the benefit of new, deeply branching genome sequences from the ancient and prolific SAR11 clade of Alphaproteobacteria and publicly available alphaproteobacterial and mitochondrial genome sequences. Using the automated phylogenomic pipeline Hal, we systematically studied the effect of taxon sampling and missing data to accommodate small mitochondrial genomes. The evidence supports a common origin of mitochondria and SAR11 as a sister group to the Rickettsiales. The simplest explanation of these data is that mitochondria evolved from a planktonic marine alphaproteobacterial lineage that participated in multiple inter-specific cell colonization events, in some cases yielding parasitic relationships, but in at least one case producing a symbiosis that characterizes modern eukaryotic life.
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http://dx.doi.org/10.1038/srep00013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3216501PMC
August 2013

Comparative functional genomics of the fission yeasts.

Science 2011 May 21;332(6032):930-6. Epub 2011 Apr 21.

Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA.

The fission yeast clade--comprising Schizosaccharomyces pombe, S. octosporus, S. cryophilus, and S. japonicus--occupies the basal branch of Ascomycete fungi and is an important model of eukaryote biology. A comparative annotation of these genomes identified a near extinction of transposons and the associated innovation of transposon-free centromeres. Expression analysis established that meiotic genes are subject to antisense transcription during vegetative growth, which suggests a mechanism for their tight regulation. In addition, trans-acting regulators control new genes within the context of expanded functional modules for meiosis and stress response. Differences in gene content and regulation also explain why, unlike the budding yeast of Saccharomycotina, fission yeasts cannot use ethanol as a primary carbon source. These analyses elucidate the genome structure and gene regulation of fission yeast and provide tools for investigation across the Schizosaccharomyces clade.
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http://dx.doi.org/10.1126/science.1203357DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3131103PMC
May 2011

Hal: an automated pipeline for phylogenetic analyses of genomic data.

PLoS Curr 2011 Feb 7;3:RRN1213. Epub 2011 Feb 7.

National Center for Biotechnology Information, Bethesda, Maryland; Peace Corps; Oregon State University and Bonzi Software Development.

The rapid increase in genomic and genome-scale data is resulting in unprecedented levels of discrete sequence data available for phylogenetic analyses. Major analytical impasses exist, however, prior to analyzing these data with existing phylogenetic software. Obstacles include the management of large data sets without standardized naming conventions, identification and filtering of orthologous clusters of proteins or genes, and the assembly of alignments of orthologous sequence data into individual and concatenated super alignments. Here we report the production of an automated pipeline, Hal that produces multiple alignments and trees from genomic data. These alignments can be produced by a choice of four alignment programs and analyzed by a variety of phylogenetic programs. In short, the Hal pipeline connects the programs BLASTP, MCL, user specified alignment programs, GBlocks, ProtTest and user specified phylogenetic programs to produce species trees. The script is available at sourceforge (http://sourceforge.net/projects/bio-hal/). The results from an example analysis of Kingdom Fungi are briefly discussed.
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http://dx.doi.org/10.1371/currents.RRN1213DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3038436PMC
February 2011

Expressed sequence tags reveal Proctotrupomorpha (minus Chalcidoidea) as sister to Aculeata (Hymenoptera: Insecta).

Mol Phylogenet Evol 2010 Oct 14;57(1):101-12. Epub 2010 Jul 14.

Department of Entomology, University of Kentucky, Lexington, KY 40546-0091, USA.

Hymenoptera is one of the most diverse groups of animals on the planet and have vital importance for ecosystem function as pollinators and parasitoids. Higher-level relationships among Hymenoptera have been notoriously difficult to resolve with both morphological and traditional molecular approaches. Here we examined the utility of expressed sequence tags for resolving relationships among hymenopteran superfamilies. Transcripts were assembled for 6 disparate Hymenopteran taxa with additional sequences added from public databases for a final dataset of 24 genes for 16 taxa and over 10 kb of sequence data. The concatenated dataset recovered a robust and well-supported topology demonstrating the monophyly of Holometabola, Hymenoptera, Apocrita, Aculeata, Ichneumonoidea, and a sister relationship between the two most closely related proctotrupomorphs in the dataset (Cynipoidea+Proctotrupoidea). The data strongly supported a sister relationship between Aculeata and Proctotrupomorpha, contrary to previously proposed hypotheses. Additionally there was strong evidence indicating Ichneumonoidea as sister to Aculeata+Proctotrupomorpha. These relationships were robust to missing data, nucleotide composition biases, low taxonomic sampling, and conflicting signal across gene trees. There was also strong evidence indicating that Chalcidoidea is not contained within Proctotrupomorpha.
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http://dx.doi.org/10.1016/j.ympev.2010.07.006DOI Listing
October 2010

The Ascomycota tree of life: a phylum-wide phylogeny clarifies the origin and evolution of fundamental reproductive and ecological traits.

Syst Biol 2009 Apr 4;58(2):224-39. Epub 2009 Jun 4.

Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA.

We present a 6-gene, 420-species maximum-likelihood phylogeny of Ascomycota, the largest phylum of Fungi. This analysis is the most taxonomically complete to date with species sampled from all 15 currently circumscribed classes. A number of superclass-level nodes that have previously evaded resolution and were unnamed in classifications of the Fungi are resolved for the first time. Based on the 6-gene phylogeny we conducted a phylogenetic informativeness analysis of all 6 genes and a series of ancestral character state reconstructions that focused on morphology of sporocarps, ascus dehiscence, and evolution of nutritional modes and ecologies. A gene-by-gene assessment of phylogenetic informativeness yielded higher levels of informativeness for protein genes (RPB1, RPB2, and TEF1) as compared with the ribosomal genes, which have been the standard bearer in fungal systematics. Our reconstruction of sporocarp characters is consistent with 2 origins for multicellular sexual reproductive structures in Ascomycota, once in the common ancestor of Pezizomycotina and once in the common ancestor of Neolectomycetes. This first report of dual origins of ascomycete sporocarps highlights the complicated nature of assessing homology of morphological traits across Fungi. Furthermore, ancestral reconstruction supports an open sporocarp with an exposed hymenium (apothecium) as the primitive morphology for Pezizomycotina with multiple derivations of the partially (perithecia) or completely enclosed (cleistothecia) sporocarps. Ascus dehiscence is most informative at the class level within Pezizomycotina with most superclass nodes reconstructed equivocally. Character-state reconstructions support a terrestrial, saprobic ecology as ancestral. In contrast to previous studies, these analyses support multiple origins of lichenization events with the loss of lichenization as less frequent and limited to terminal, closely related species.
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http://dx.doi.org/10.1093/sysbio/syp020DOI Listing
April 2009

Genome sequencing and analysis of the biomass-degrading fungus Trichoderma reesei (syn. Hypocrea jecorina).

Nat Biotechnol 2008 May 4;26(5):553-60. Epub 2008 May 4.

Los Alamos National Laboratory/Joint Genome Institute, PO Box 1663, Los Alamos, New Mexico 87545, USA.

Trichoderma reesei is the main industrial source of cellulases and hemicellulases used to depolymerize biomass to simple sugars that are converted to chemical intermediates and biofuels, such as ethanol. We assembled 89 scaffolds (sets of ordered and oriented contigs) to generate 34 Mbp of nearly contiguous T. reesei genome sequence comprising 9,129 predicted gene models. Unexpectedly, considering the industrial utility and effectiveness of the carbohydrate-active enzymes of T. reesei, its genome encodes fewer cellulases and hemicellulases than any other sequenced fungus able to hydrolyze plant cell wall polysaccharides. Many T. reesei genes encoding carbohydrate-active enzymes are distributed nonrandomly in clusters that lie between regions of synteny with other Sordariomycetes. Numerous genes encoding biosynthetic pathways for secondary metabolites may promote survival of T. reesei in its competitive soil habitat, but genome analysis provided little mechanistic insight into its extraordinary capacity for protein secretion. Our analysis, coupled with the genome sequence data, provides a roadmap for constructing enhanced T. reesei strains for industrial applications such as biofuel production.
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http://dx.doi.org/10.1038/nbt1403DOI Listing
May 2008

A phylogenomic analysis of the Ascomycota.

Fungal Genet Biol 2006 Oct 15;43(10):715-25. Epub 2006 Jun 15.

Department of Botany and Plant Pathology, Oregon State University, Corvallis, 97333, USA.

An automated procedure was developed to extract orthologous sequences from fungal genomes and incorporate them into phylogenomic analyses in a timely and efficient manner. This approach involves parsing an all versus all BLASTP search of 17 proteomes and creating a similarity matrix from e-values, which is then used to cluster proteins into related groups by means of a Markov Clustering algorithm. After performing this analysis at different stringency levels, 854 single copy protein clusters, which were ubiquitously distributed in all 17 proteomes, were identified. These clusters were culled to include only those clusters where all proteins had best hits to and received hits from a protein within the same cluster. The final data set included gapless alignments for 781 clusters of orthologous sequences that were concatenated into one super alignment containing 195,664 amino acid characters. Neighbor-joining distance and maximum likelihood analyses resulted in identical topologies and all except one node received 100% bootstrap support. The node supporting Stagonospora nodorum's position received 83% support or higher; it was also the only taxon differentially resolved in the maximum parsimony analyses. All analyses resolved the two derived subphyla Pezizomycotina and Saccharomycotina, and Schizosaccharomyces pombe as an early diverging lineage of the Ascomycota. Importantly, these analyses resolved the Leotiomycetes as the sister group to the Sordariomycetes, a region of the Ascomycota phylogeny that has remained problematic in molecular phylogenetic studies of more limited character sampling. Additional phylogenetic analyses which included orthologous sequences from an unannotated ascomycotan genome (e.g., Coccidioides immitis) and subsets of orthologs with different characteristics supported this topology. Phylogenetic analyses of the 595 orthologs which included C. immitis resulted in an identical topology to the previous 781 ortholog analysis and correctly placed C. immitis in the Eurotiomycetes. This demonstrated the correct identification of orthologs and the ability to incorporate unannotated genomic data into a common phylogenetic analysis.
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http://dx.doi.org/10.1016/j.fgb.2006.05.001DOI Listing
October 2006

Functional analysis of all nonribosomal peptide synthetases in Cochliobolus heterostrophus reveals a factor, NPS6, involved in virulence and resistance to oxidative stress.

Eukaryot Cell 2005 Mar;4(3):545-55

Torrey Mesa Research Institute, San Diego, California, USA.

Nonribosomal peptides, made by nonribosomal peptide synthetases, have diverse biological activities, including roles as fungal virulence effectors. Inspection of the genome of Cochliobolus heterostrophus, a fungal pathogen of maize and a member of a genus noted for secondary metabolite production, revealed eight multimodular nonribosomal peptide synthase (NPS) genes and three monomodular NPS-like genes, one of which encodes a nonribosomal peptide synthetase/polyketide synthase hybrid enzyme presumed to be involved in synthesis of a peptide/polyketide molecule. Deletion of each NPS gene and phenotypic analyses showed that the product of only one of these genes, NPS6, is required for normal virulence on maize. NPS6 is also required for resistance to hydrogen peroxide, suggesting it may protect the fungus from oxidative stress. This and all other nps mutants had normal growth, mating ability, and appressoria. Real-time PCR analysis showed that expression of all NPS genes is low (relative to that of actin), that all (except possibly NPS2) are expressed during vegetative growth, and that expression is induced by nitrogen starvation. Only NPS6 is unfailingly conserved among euascomycete fungi, including plant and human pathogens and saprobes, suggesting the possibility that NPS6 activity provides oxidative stress protection during both saprobic and parasitic growth.
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http://dx.doi.org/10.1128/EC.4.3.545-555.2005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1087798PMC
March 2005

Deletion of all Cochliobolus heterostrophus monofunctional catalase-encoding genes reveals a role for one in sensitivity to oxidative stress but none with a role in virulence.

Mol Plant Microbe Interact 2003 Nov;16(11):1013-21

Torrey Mesa Research Institute, 3115 Merryfield Row, San Diego, CA 92122, USA.

The genome of the maize pathogen Cochliobolus heterostrophus encodes three unlinked monofunctional catalase-encoding (CAT) genes that singly or in combination could offer protection against the harmful effects of oxidative stress. Phylogenetic analysis placed the CAT2 and CAT3 proteins in a cluster with large subunit catalases (CAT3 has a secretory signal sequence and was grouped with known secreted catalases), whereas CAT1 clustered with small subunit catalases. Single, double, and triple cat mutants were created and screened for sensitivity to hydrogen peroxide and altered virulence on maize. All mutants deficient in CAT3 had enhanced sensitivity to hydrogen peroxide, as compared with wild type or with mutants deficient in CAT1, CAT2, or both. All catalase-deficient mutants had normal virulence to maize. Thus, the secreted CAT3 protein protects the fungus from oxidative stress during vegetative growth, but members of this enzyme family, alone or in combination, are not essential for virulence.
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http://dx.doi.org/10.1094/MPMI.2003.16.11.1013DOI Listing
November 2003

A novel class of gene controlling virulence in plant pathogenic ascomycete fungi.

Proc Natl Acad Sci U S A 2003 May 2;100(10):5980-5. Epub 2003 May 2.

Department of Plant Pathology, Cornell University, Ithaca, NY 14853, USA.

Insertional mutants of the fungal maize pathogen Cochliobolus heterostrophus were screened for altered virulence. One mutant had 60% reduction in lesion size relative to WT but no other detectable change in phenotype. Analysis of sequence at the insertion site revealed a gene (CPS1) encoding a protein with two AMP-binding domains. CPS1 orthologs were detected in all Cochliobolus spp. examined, in several other classes of ascomycete fungi, and in animals but not in basidiomycete fungi, bacteria, or plants. Phylogenetic analysis suggested that CPS1 represents a previously undescribed subset of adenylate-forming enzymes that have diverged from certain acyl-CoA ligases, which in bacteria are involved in biosynthesis of nonribosomal peptides or polyketidepeptide hybrids. Disruption of CPS1 caused reduced virulence of both race T and race O of C. heterostrophus on maize, of Cochliobolus victoriae on oats, and of Gibberella zeae on wheat. These results suggest that CPS1 functions as a general fungal virulence factor in plant pathogenic ascomycetes.
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http://dx.doi.org/10.1073/pnas.0931375100DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC156312PMC
May 2003